Hautere/Solander Island is a rugged, inhospitable lump of an island lying in the western approaches to Foveaux Strait. About 40 km south of Fiordland and 70 km north-west of Stewart Island, it is 1.6 km on its longest axis, with cliffs rising steeply to the 330 m summit. The only flat land is a 10 ha forested plateau east of the summit.
The island was an early focus for western commerce in New Zealand, with sealing gangs visiting from about 1803, and whalers seeking sperm whales offshore from about 1838. The sealers sought skins of the New Zealand fur seal (Arctocephalus forsteri), which have since recovered from near extirpation and are abundant around the island’s coast. Occasional subantarctic fur seals (A. tropicalis) also visit, but the boulder-strewn bays and steep headlands do not provide suitable habitat for sea lions or elephant seals.
Sealing gangs were probably responsible for the introduction of weka to Solander Island. The genetics and plumage colouration of the birds indicates that they were brought from Fiordland rather than Stewart Island, most likely from the important sealing grounds of Dusky Sound. Only brown morph birds are present, suggesting that the founding population was small (black morph birds are common on the few islands where weka still occur in western Fiordland).
Weka almost certainly had a profound impact on the birdlife of Solander Island. Burrowing petrels are scarce, and several landbird species likely to have present have never been recorded, including banded rail, snipe and fernbird. Sooty shearwaters still breed around the edge of the summit plateau, with four smaller petrel species (mottled petrel, fairy prion, broad-billed prion and common diving petrel) hanging on in low numbers in steep rocky sites that offer some protection from weka. We found remains of both prion species that had likely been killed and eaten by weka, and saw occasional broad-billed prions flying over the island. In contrast, I found banded rails present on nearby (weka-free) Little Solander Island in 1985, and we estimated 300,000 pairs of diving petrels to be breeding on the 4 ha island. Little Solander also has New Zealand’s southernmost gannet colony, and we counted 13 adults roosting there from the helicopter as we departed on 23 May 2016.
The most abundant and conspicuous birds on Solander Island are the Buller’s mollymawks, with at least 6,000 pairs breeding. Although the total population is smaller than on the Snares Islands (the only other breeding site for the southern subspecies), the birds occur at much higher densities on Solander, which is about a quarter the size. Despite having spent many months on the Snares Islands, I had never seen so many Buller’s mollymawks filling the sky as we saw on Solander Island whenever the gales eased. When the winds are too strong, rafts of mollymawks wait offshore rather than risking damaging their 2-metre wingspans landing in turbulent conditions.
Buller’s mollymawks breed in winter and were the focus of our visit, as we tracked foraging trips of adults caring for chicks. Most chicks were large enough to be left alone, but some found it tough going in the torrential rain. At least one pair was still incubating an egg when we departed, and a few pairs were still guarding young chicks.
The other winter-breeding seabird on the island is the Fiordland crested penguin, which returns to the island in late June or early July before laying in July or August. We saw only a single adult during our 10-27 May visit.
Southern black-backed gulls and red-billed gulls occurred in low numbers around the coast, and there were at least 40 white-fronted terns present. We also saw several variable oystercatchers (black morph) and a white-faced heron.
Apart from weka, the commonest native landbirds on the island were red-crowned parakeets, tomtits, bellbirds and silvereyes, plus there were a few grey warblers and fantails (pied morph only). We saw only male tomtits near the coast, but females predominated in the summit forest. Even more surprisingly, we recorded only male bellbirds during the entire trip, suggesting that females are scarce and secretive on the island. The two pipits seen were the first recorded on the island since 1933.
Dunnocks are the only common introduced bird on the island (apart from the ‘introduced native’ weka), plus we saw a few starlings, blackbirds and a greenfinch. Visiting seabirds, including those seen offshore, included southern royal albatross, northern giant petrel, Antarctic fulmar, Cape petrel, black shag, spotted shag and subantarctic skua.
Hautere/Solander Island is a Specially Protected Area within Fiordland National Park. The islands are managed by the Department of Conservation, who authorised our research visit.